1. Field of the Invention
The present invention relates to a technology which controls participation of another communication terminal in a session used for content data transmission between communication terminals.
2. Description of the Related Art
In recent years, responding to a demand for reducing cost and time, a communication system has become popular which provides a video conference or a telephone call via a communication network such as the Internet. In this kind of a communication system, when communications between communication terminals are started, content data including image data and audio data is transmitted and received, and thus, a video conference, a telephone call, etc., can be realized.
Further, in a communication system used in the form of a call center, etc., a call request, a destination of which is a call center, is provided to a communication terminal selected from a plurality of communication terminals by a switch, and a session between two communication terminals is established (refer to PLT 1). In this kind of a communication system, in order to provide necessary security, there is a case where another communication terminal is not allowed to participate in a session between two communication terminals.
On the other hand, in a communication system used in the form of a video conference, etc., there is a method in which a call is established among multiple sites by allowing another communication terminal to participate in a session in which content data is transmitted between communication terminals (refer to PLT 2). In this type of a communication system, a communication state of each communication terminal is maintained, and, in the case where a destination communication terminal is already in a state of communication when a communication terminal requests a communication start, the communication terminal as a communication start request source is allowed to participate in a session in which the destination communication terminal is participating.
In recent years, responding to a demand for space saving, diversification of businesses, etc., it has come to be desired to establish a communication system which can be used in multiple forms. According to a communication management system described in PLT 3, the communication management system establishes a session with limited participation and a session with unlimited participation based on a selected button displayed in a making-a-call confirmation dialog box of a communication terminal.